Turn off keyboard or mouse when not in use

As has been found by several posters, a keyboard or mouse that is inadvertently left on and hiding underneath something can hijack a computer's input from both keyboard and trackpad, and effectively make it not work at all. When it receives input from two distinct locations, the computer may get confused and stumble. Similarly, turn off Bluetooth sharing on your phone when not in use either. If unsure how to turn it off, simply remove the battery.